This standard specifies test methods, test requirements and classifications for air handling units, which are supplying and/or extracting air via a ductwork ventilating/conditioning a part or the whole of the building. This standard is not applicable to the following: a) air conditioning units serving a limited area in a building, such as fan coil units; b) units for residential buildings; c) units producing ventilation air mainly for a manufacturing process. Except for the thermal and acoustic performance of the casing, the test methods and requirements are applicable to both complete units and any separate sections. The filter bypass test is not applicable to the testing of high efficiency particulate air filters (HEPA). NOTE HEPA filters are recommended to be installed downstream of the air handling unit. Such installations should be leak tested in accordance with the appropriate filter standards. The test method for the thermal performance of the casing is applicable to the comparison of different constructions, but not to the calculation of thermal losses through casing or the risk of condensation. Similarly, the test method for the acoustic performance of the casing is applicable to the comparison of different constructions, but not to the provision of accurate acoustic data for specific units.